text: The central component of GEOTRACES is a series of [http://www.geotraces.org/cruises/cruise-summary cruises spanning the global ocean] and sampling the full water column. These dedicated GEOTRACES cruises collect seawater for analysis of a wide range of trace element and isotopes. This strategy is guided by the principle that more will be learned through complementary investigation of multiple trace elements than can be achieved in an exhaustive study of one element in isolation.